Rotary mechanical seal



April 28, 1959 F. E. PAYNE 2,884,266

ROTARY MECHANICAL SEAL Original Filed Sept. 20, 1954 7 se a 14 4 .2

' INVENTOR. FRANK E. PAYNE FIGLZ United States Patent Oflice 2,884,266Patented Apr. 28, 1959 ROTARY MECHANICAL SEAL Frank E. Payne, Glencoe,Ill., assignor to Crane Packing Company, Chicago, 111., a corporation ofIllinois Original application September 20, 1954, Serial No. 457,194.Divided and this application August 18, 1955, Serial No. 529,204

1 Claim. (Cl. 28611) The present invention relates to improvements inshaft seals of the type shown and described in my copending applicationSerial No. 457,194, filed September 20, 1954, for Rotary MechanicalSeal, of which application the present application is a true division.

Specifically the invention relates to an improved rotary mechanical sealfor efiecting a seal against the passage of fluid between a shaft and amachine casing within which the shaft is rotatably mounted. Theinvention relates to that type of sealing device in which the sealingeffeet between the relatively moving parts occurs at radially extendingsurfaces and wherein a so-called running seal is eifected between themoving parts.

Seals constructed in accordance with the principles of the presentinvention may assume various forms and, in the form illustrated herein,improved operating characteristics have been attained while at the sametime ease of assembly of the seal has been facilitated.

In the assembly of seals of this type it is desirable that theinstallation be made with a minimum of eflfort so that the operator maydevote but little time and thought to the assembly of the seal withwhich each pump is equipped. Such seals are a specialty and a moreeffective and proper assembly can be performed by the seal manufacturerat the factory than can be attained by individual installation so thatthereafter the preassembled seals may be handled as completepackage-type assemblies or units which are placed in position in therecess provided for them in the pump casing.

Briefly, seals of the type disclosed herein involve package-type unitsincluding a seal washer, bellows, spring and ferrule assembly, alldesigned for telescopic assembly upon one another wherein thesub-assembly of the washer, bellows and ferrule is held against removalby the application of an adhesive which is purported to hold the flangedend of the bellows in contact with the end wall of the retainer. Theapplication of the adhesive is usually accomplished by a sprayingoperation.

The assembly of seals of this type in the manner briefly outlined abovecannot be accomplished in a uniform manner and with uniform resultsinasmuch as the spraying operation is a manual one under the control ofthe operator who may apply too little or too much of the adhesive sothat after the sub-assembly has been applied to the retainer differentadhesive characteristics will obtain. It has been found that duringnormal assembly operations, seals of this type will withstand a tensilestrength of approximately thirty pounds on the flange but occasionallywhere too little adhesive has been applied the parts will separate undera tensile pull of two or three pounds. Furthermore, the use of anadhesive for effecting the assembly requires a drying period of approximately sixteen hours which requires special handling and which thusconsiderably contributes to the overall cost of the seal.

The present invention in one form thereof is designed to overcome theabove limitations thatare attendant upon I acteristics.

the assembly of seals of this character and toward this end itcontemplates the provision of a novel form of clamping means whereby theinturned or flanged end of the elastomeric bellows may be preloaded uponthe cylindrical wall of the retainer against dislodgement without theuse of an adhesive.

In seals of this type undue external pressures developed on the outsideof the sealing bellows may cause the bellows to enter the intersticesbetween the various spring convolutions and, not only is the bellowssubject to the pinching action of the spring, but such elongation orstretching of the bellows may pull the washer away from its seat, thusopening up the seal. It may also pull or strip the bellows flange awayfrom the rear wall of the retainer.

According to the present invention means are provided for obviating thisdifficulty and, toward this end, provision is made whereby externalpressures developed outside of the bellows may enter between the flangedend of the bellows and the end wall of the retainer so as to force theflexible portion of the bellows forwardly and counteract any tendencyfor the seal faces to open due to stretching of the bellows under theinfluence of external pressures. In carrying out this object, theinvention contemplates the provision of a recess in the material of thebellows, the recess being formed by virtue of the provision of a void orrecess in the inturned flanged end of the bellows on the rear sidethereof so that pressure developed within this recess between theretainer wall and flanged end of the bellows will assist the action ofthe spring in maintaining the seal faces closed.

The provision of a rotary mechanical seal of the char.- acter brieflyoutlined above and possessing the advan tages briefly set forth abovebeing among the principal objects of the invention another object is toprovide a seal of this character which is extremely compact in itsdesign and which, although it employs a compression spring capable of alarge degree of contractional and expansional movements, is relativelyshort with respect to its overall length thereby enabling the seal as awhole to be used in installations where space is at a premium.

Other important objects and advantages of the present invention willbecome more readily apparent as the nature of the invention is betterunderstood.

In the accompanying single sheet of drawings forming a part of thisspecification a preferred embodiment of the invention has been shown.

In these drawings:

Fig. 1 is a fragmentary quarter section view taken transversely throughone form of seal assembly constructed in accordance with the principlesof the present invention, and

Fig. 2 is a sectional view taken substantially along the line 2--2 ofFig. 1. I

Referring now to the drawings in detail, the seal assembly of thepresent invention has been shown as being applied to a pump constructionwhich may be a high pressure jet pump including a pump housing 10 havingan opening 12 formed therein provided with a counterbore 14-. The pumpshaft 16 extends through the opening 12 and carries the usual pumpimpeller 18. The seal assembly is designated in its entirety at 20 andincludes a sealing washer 22 having a forwardly extending nose portion24 on which there is formed a substantially fiat annular radiallydisposed sealing surface 26 designed for running sealing engagement witha similarly flat sealing surface 28 provided on the hub portion of theimpeller. The washer 22 may be formed of any of a number of knownmaterials which have been proven efiective as sealing elements as forexample a molded thermo-setting resin having dispersed therein metalparticles for better heat conductivity and good wear char- The washer 22is at least partially nested within a generally cylindrical cup-shapedretainer or shell 30 in the form of a light sheet metal stamping ofone-piece construction having an outer cylindrical wall 32, an innercylindrical wall 34, generally known as a center post, and aninterconnecting radial wall 36. The washer 22 is slidable upon the innercylindrical wall 34 and a pair of diametrically opposed outwardly struckribs 38 are formed on the wall 34- and extend into aligned longitudinalgrooves 40 formed in the inner cylindrical bore of the washer 22. Theribs and grooves permit sliding movement of the washer on thecylindrical wall while preventing relative sliding movement betweenthese parts.

The retainer 30 is pressed into the counterbore 14 of the housing and anoutwardly extending radial flange 42 formed on the retainer serves tolocate the latter with reference to thesealing surface 28 provided onthe hub of the impeller 18.

In order to effectively seal the washer 22 with respect to the retainer30 and consequently with respect to the housing 10, a flexible sleeve orbellows member 50 which is preferably formed of an elastomeric materialsuch as rubber, either natural or synthetic, or a combination of thetwo, is provided with a forward thickened cylindrical region 52 which istelescopically received over the rear end of the washer 22 and which isclamped thereto by means of a generally cylindrical metal ferrule 54.The inside diameter of the ferrule 54 is somewhat less than the combinedradial extent of the washer 22 and sleeve 50 so that the cylindricalportion 52 of the bellows may be preloaded upon the outer surface 56 ofthe washer. An inclined rearwardly extending flange 58 formed on theferrule limits the forward axial movement of the ferrule during assemblyoperations when the washer 22, sleeve 50' and ferrule 54 are assembledone upon another. The forward end of the ferrule 54 is flared outwardlyas at 59 to guide the ferrule over the thickened portion 52 of thesleeve during such assembly operations.

The sleeve or bellows 50 is provided with an outside conical surface 60,the slope of which is substantially the same as the slope of the conicalportion 58 of the ferrule 54 and the thickened portion of the bellowsmerges with an intermediate flexible portion 62. The rear end of thebellows 50 is turned inwardly as at 66 to provide a flange portion, theinner edge of which terminates in a re-entrant thickened portion 68. Inorder that the seal shall function properly, it is necessary that there-entrant thickened portion 68 of the bellows member 50 be held firmlyagainst the inner face of the radial end wall 36 of the retainer 30 and,heretofore in seals of this general nature, adherence of the inturnedflange of the bellows member has been effected by means of a suitableadhesive. In the present instance however this adherence is maintainedby preloading the thickened portion 68 upon the retainer center post 34.Toward this 'end a metal band or ferrule 70 which is L-shaped in crosssection has a cylindrical flange 72 which surrounds the thickenedportion 68 and a radial flange 74 which bears against the forward faceof the portion 68. The diameter of the ferrule is such that when thesame is in position over the thickened portion 68, the latter iscompressed between the cylindrical wall 72 of the ferrule and thecylindrical wall 34 of the retainer thus compressing the thickenedportion on the latter cylindrical wall. A coil spring 80 which may be ofslight conical configuration bears at one end against the radial flange74 of the ferrule 70 and the other end of the spring is seated within arecess 82 provided in the rear face of the washer 22. The recess 82 iscomparatively deep and allows the use of a spring 80 which iscomparatively long and which therefore has an effective sealing actionon the'washer 22. The fact that the recess '82 in the washer isrelatively deep and also the fact that the spring 86 is of conicalconfiguration mutually :con-

tributes toward the provision of a seal assembly which may beconstructed with an overall length which is considerably shorter thanwould otherwise be possible.

The central opening provided in the ring member 70 is of a diametersufiiciently great to enable the ring member to pass over the drivingribs 38 on the center post 34 during initial assembly operations.

The bellows member 59 is molded so as to provide a slight clearance asshown at J0 on the rear side of the bellows between the radial retainerwall 36 and bellows, this clearance being provided for the purpose ofestablishing a hydraulic balance on the opposite sides of the bellows.In Fig. l the seal is shown in its installed position with the bellowsshown in the position it will assume before any fluid pressure isapplied exteriorly thereof. While the exact shape that the bellows willassume when pressure is exerted upon it from the outside cannot beascertained, it is known of course that such pressure will tend tocollapse the bellows inwardly to a certain extent depending upon theamount of pressure in the fluid to be sealed. Without the provision ofthe recess 5%) it may be observed that any tendency for the bellows tocollapse will blow the bellows, so to speak, inwardly so that it willhug the convolutions of the spring 83 thus stretching the bellows andwhen the pressure is sufliciently high, this stretching of the bellowsmay have the effect of opening up the two seal surfaces 26 and 28 byvirtue of the washer 22 being drawn rearwardly under the stretchingaction of the bellows. Where the recess $8 is provided however ahydraulic balance is obtained whereby fluid pressure may pass around therear end of the bellows and move the same forwardly thus effectivelyincreasing the length of the flexible portion of the bellows so thatupon inward movement thereof ample material is supplied and there willbe no tendency for the material to stretch and pull the washer 22 awayfrom the seat 18. This clearance 90 at the rear end of the bellowsconstitutes one of the important features of the present invention.

The provision of the clearance space or recess 90 which permits externalpressures developed outside of the bellows to pass behind the bellowsand assist in moving the same forwardly is especially important forseals which contemplate high external pressures. With seals designed foruse in accommodating high internal pressures the recess 90 may beomitted and the clamping band or ferrule 70 will still effectively serveits function of preventing pulling of the inturned flange radiallyoutwardly or forwardly and away from. the rear wall 36 of the retaineror shell 30.

In compliance with Title 35, US. ,Code, Section 22, a preferred form ofthe invention has been shown in the drawings and described herein, butit should be understood that the invention is not limited to thespecific disclosure made, and that the appended claim should beconstrued as broadly as the prior art will permit.

What I claim is:

A seal for relatively rotatable elements comprising in combination. aWasher having a radially outer surface, a deep annular recess in therear face thereof extending into the radial confines of the outersurface, a deformable sleeve of elastomeric material, said sleeve havinga radially disposed, inwardly extending flange at one end, the other endthereof being telescoped over the said outer surface of the washer andthe region intermediate the ends being deformable to accommodaterelative axial movement between the ends of the sleeve, means forcompressing the telescoping end of the sleeve against the outer surfaceof the Washer to form a fluid-tight connection therebetween, a retainerhaving a cylindrical portion and a radial wall disposed rearwardly ofsaid washer and against which at least a portion of said radiallydisposed flange bears, said inwardly extending flange having an enlargedre-entrant portion immediately surrounding the cylindrical wallof theretainerand extendingaxially toward the washer, a ring disposed withinsaid sleeve and References Cited in the file of this patent having aportion surrounding said re-entrant portion and UNITED STATES PATENTSserving to compress the latter upon the cylindrical portion of theretainer, and a compresison spring having 116-23598 Haake 1954 one enddisposed in the annular recess in the water and 5 2,467,543 Voytech P19, 1949 its other end bearing against the ring within the sleeve,2,610,075 Haake Sep 9, 9 the axial extent of the flange beingsubstantially equal to 2,671,407 Higbie Mar. 9, 1954 the axial depth ofthe recess to avoid unduly lengthening 2,815,967 Payne et a1 Dec. 10,1957 the seal axially by virtue of the presence of the said flange. 10

